The world of underwater photography presents one of the most difficult, if not the most difficult, environments in which to carry forward the photographic arts. However, the vast array of fascinating and exciting subjects which are available to photographers together with the enjoyment and challenge of underwater activity have continued to stimulate underwater photographers in a neverending quest for more and more interesting photographic subjects and settings. One of the significant challenges in the world of underwater photography is presented to the manufacturers of cameras adapted for use in this extremely harsh and demanding environment. Underwater cameras must, of course, maintain complete integrity or water-tight properties to preserve the internal operating mechanism and film. Since underwater photography often takes place at substantial depths, underwater cameras must be able to sustain a great pressure difference between the deep water outer environment and the sealed interior portion of the camera. In addition, underwater photography taking place in the ocean subjects the underwater camera to the corrosive actions of the ocean's salt water and other corrosive elements. Finally, since underwater cameras are operated by photographers who are also restricted in their ability to operate in this harsh environment due to equipment they wear and use to sustain and protect themselves, underwater cameras must be rugged and durable and must be made in a manner permitting easy manipulation and operation of the camera.
Thus far, however, underwater camera manufacturers have not provided cameras which readily meet these challenges of the underwater photographic environment. While the construction of underwater cameras differs somewhat between manufacturers, all generally include a water-tight housing which supports a camera mechanism therein. The camera mechanism includes a generally conventional film transport and shutter mechanism together with a viewer or range finder and an optical coupling system for the lens. In order to properly operate the camera mechanism, one or more control elements are often coupled through apertures in the housing between the exterior and interior of the water-tight housing. These apertures are sealed by various resilient sealing structures to protect the water-tight camera interior.
While underwater cameras have advanced through the years, their advance has generally lagged behind their above water counterparts in features and ease of operation due in part to the difficult environment in which underwater cameras must operate. For example, in non-underwater or above water cameras, most professional photographers and serious amateurs alike have available a vast array of cameras providing through-the-lens viewing which greatly enhances their capability. Through-the-lens viewing denotes those cameras in which the optical path for the photographer's viewing of the to-be-photographed image as well as the optical path to the to-be-exposed film, both proceed through the main camera lens. In contrast, non through-the-lens cameras, generally referred to as rangefinder or viewfinder cameras, provide separate optical paths and lens systems for the photographer's view of the to-be-photographed image. As a result, in non through-the-lens cameras, the photographer does not actually see the same image through the viewfinder as the exposed film will see through the main camera lens. While rangefinder or viewfinder-type cameras are adequate for the general public, serious amateurs and professional photographers including underwater photographers have substantial need of through-the-lens viewing to properly practice their art.
To meet the desire of underwater photographers for through-the-lens cameras, practitioners in the art have provided special housings which receive one or more types of single lens reflex cameras within a special dome housing. Single lens reflex cameras are extremely popular in the non-underwater arts and provide the most pervasive type of through-the-lens camera structure. Because of the compact dimensions of single lens reflex cameras, they are generally the camera of choice for inclusion within such domed housings. Single lens reflex cameras acquire their through-the-lens viewing capability by using a movable mirror within the film exposure optical path to divert the through-the-lens image to the viewer optical system prior to film exposure. At the time of film exposure, the lens pivots out of the optical path allowing the film to be exposed by the main camera lens image. While the use of single lens cameras within domed housings provides through-the-lens viewing, a problem arises in that the dome itself, which must of course be transparent, becomes an operative part of the camera optic system and, in essence, represents a lens which must be matched to the main camera lens to properly focus an image. The uncertainties and variations of this additional "lens" provided by the dome structure generally degrades the photographic image and has been found lacking by most professional underwater photographers.
It is generally believed that the most pervasive and popular underwater camera provided by camera manufacturers is the Nikonos V manufactured by the Nikon Corporation. The Nikonos V comprises a rangefinder or viewfinder camera which does not provide through-the-lens viewing but is nonetheless extremely popular. The camera provides a sealed housing together with manually operated shutter and film advance mechanisms, a mechanical exposure counter, and a an electronically controlled exposure system.
While the foregoing described prior art underwater cameras have, to some extent, facilitated underwater photography, they have in many instances failed to provide several of the important features enjoyed by cameras not adapted to the underwater photographic environment. There remains, therefore, a need in the art for an underwater camera which facilitates through-the-lens viewing without degrading image quality and which provides increased feature capability and ease of operation.